Elastic shaft couplings of this type are known in numerous different embodiments with axial force flow or radial force flow, with one or more resilient coupling bodies that are connected in series or in parallel. Examples are the shaft couplings of DE 100 13 412 [U.S. Pat. No. 6,464,587] or DE 10 2005 055 605 [U.S. Pat. No. 7,497,782] that are published.
Besides the compensation of radial and/or axial offset of drive aggregate and/or output aggregate, these elastic shaft couplings serve in particular for absorbing torsional vibrations and torque peaks between input and output assemblies as generated, for example, by an irregularly running diesel engine.
Each coupling is designed for a predetermined operating range in which it can reduce the rotational vibrations of the complete system in a particularly good manner. In certain applications, a plurality of couplings of the above-described type is connected together, for example, to achieve an optimal damping over a wide speed range of the drive. Here, a first coupling absorbs the rotational vibrations at low speeds and a second coupling absorbs the rotational vibrations at high speeds. As an example for such a coupling arrangement, EP 0 626 523 [U.S. Pat. No. 5,545,089] is to be mentioned in which a coupling stage with a linear characteristic and a coupling stage with a progressive characteristic are interconnected to form a two-stage coupling arrangement. In this manner, a coupling can be provided that is able to compensate for rotational vibrations over a wide operating range of the drive.
Two-stage couplings that take advantage of the effect of different characteristics of the coupling bodies for compensation of rotational vibrations perform their task substantially in a very reliable manner; however, they have the problem that here, on the one hand, the operating range of the complete system is still limited by the sum of operating ranges of the respective coupling bodies and, on the other hand, the compensation of torsional vibrations in the transition range from one to the other coupling stage is still in need of improvement.